Use this restrictor if you are using a Senior Max engine in TAG-Restricted under KA - if you use this restrictor under KA conditions you must be 5kg heavier than the standard weight for the class. So it is ideal for someone slightly heavier who cannot quite make the weight for the class (if you want to run the normal weight for the class you should use the MCRM part number as your restrictor
Use this restrictor if you are using a Senior Max engine in TAG-Restricted under KNSW
Use this restrictor if you are using a Junior Max engine in TAG-Restricted under KA